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gpio: Restrict usage of GPIO chip irq members before initialization

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GPIO chip irq members are exposed before they could be completely
initialized and this leads to race conditions.

One such issue was observed for the gc->irq.domain variable which
was accessed through the I2C interface in gpiochip_to_irq() before
it could be initialized by gpiochip_add_irqchip(). This resulted in
Kernel NULL pointer dereference.

Following are the logs for reference :-

kernel: Call Trace:
kernel:  gpiod_to_irq+0x53/0x70
kernel:  acpi_dev_gpio_irq_get_by+0x113/0x1f0
kernel:  i2c_acpi_get_irq+0xc0/0xd0
kernel:  i2c_device_probe+0x28a/0x2a0
kernel:  really_probe+0xf2/0x460
kernel: RIP: 0010:gpiochip_to_irq+0x47/0xc0

To avoid such scenarios, restrict usage of GPIO chip irq members before
they are completely initialized.

Signed-off-by: Shreeya Patel <shreeya.patel@collabora.com>
Cc: stable@vger.kernel.org
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
This commit is contained in:
Shreeya Patel 2022-03-21 19:02:41 +05:30 committed by Bartosz Golaszewski
parent 3123109284
commit 5467801f1f
2 changed files with 28 additions and 0 deletions
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19
drivers/gpio/gpiolib.c
View File

@ -1404,6 +1404,16 @@ static int gpiochip_to_irq(struct gpio_chip *gc, unsigned int offset)
{
struct irq_domain *domain = gc->irq.domain;
#ifdef CONFIG_GPIOLIB_IRQCHIP
/*
* Avoid race condition with other code, which tries to lookup
* an IRQ before the irqchip has been properly registered,
* i.e. while gpiochip is still being brought up.
*/
if (!gc->irq.initialized)
return -EPROBE_DEFER;
#endif
if (!gpiochip_irqchip_irq_valid(gc, offset))
return -ENXIO;
@ -1593,6 +1603,15 @@ static int gpiochip_add_irqchip(struct gpio_chip *gc,
acpi_gpiochip_request_interrupts(gc);
/*
* Using barrier() here to prevent compiler from reordering
* gc->irq.initialized before initialization of above
* GPIO chip irq members.
*/
barrier();
gc->irq.initialized = true;
return 0;
}

9
include/linux/gpio/driver.h
View File

@ -221,6 +221,15 @@ struct gpio_irq_chip {
*/
bool per_parent_data;
/**
* @initialized:
*
* Flag to track GPIO chip irq member's initialization.
* This flag will make sure GPIO chip irq members are not used
* before they are initialized.
*/
bool initialized;
/**
* @init_hw: optional routine to initialize hardware before
* an IRQ chip will be added. This is quite useful when